BACKGROUND AND AIM: Endoscopic submucosal dissection (ESD) is an acceptable treatment for superficial esophageal squamous cell carcinoma (ESCC) even in elderly patients. However, studies on the prognostic factors in very elderly patients are limited. Therefore, we aimed to explore the prognostic factors affecting overall survival (OS) in patients aged ≥ 80 with superficial ESCC who underwent ESD. METHODS: This study included 155 patients aged ≥ 80 who underwent ESD for superficial ESCC. Clinicopathological findings and long-term outcomes were examined. The prognostic nutritional index (PNI) and geriatric nutritional index (GNRI) were used to assess pre-treatment nutritional status. RESULTS: Twenty-nine patients (18.7%) were aged ≥ 85. Thirty-five (22.6%) and 61 (39.4%) patients had a GNRI <
92 and PNI <
45, respectively. Metastatic relapse was observed in five cases, four (80%) of which resulted in death due to the primary disease. The median OS of all patients was 86 months. Although factors specifically associated with disease-specific survival were not identified, GNRI, PNI, comorbidity, and physical status were associated with OS. In multivariate analysis, age ≥ 85 years (p = 0.03), GNRI (p <
0.01), and PNI (p <
0.01) remained factors associated with OS. Patients aged ≥ 85 with either GNRI ≥ 92 or PNI ≥ 45 had a median OS of 106 months, whereas those aged ≥ 85 with GNRI <
92 had a median OS of 12 months. CONCLUSIONS: GNRI and PNI are important indicators for assessing the suitability of ESD in elderly patients aged ≥ 80. These indices can help predict OS and guide clinical decision-making for this patient population.